Work feed mechanism



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Aug. 11, 1970 w. M; SHIELDS WORK FEED MECHANISM Filed April 11, 1968 A TTOENEV United States Patent 3,523,632 Patented Aug. 11, 1970 US. Cl.226150 3 Claims ABSTRACT OF THE DISCLOSURE A device for intermittentlyfeeding work stock material to a stamping or like machine and includinga reciprocal carriage member having a gripper provided thereon, meansfor varying the feed stroke of the carriage and damping it, a gripper tohold the stock during retraction of the carriage member and anelectro-pneumatic system for controlled operation thereof.

BACKGROUND OF THE INVENTION Mechanical means are commonly known forfeeding stock materials to punch presses, stamping machines and thelike. They generally include a power operated device for gripping thestock, usually in strip form, and moving it into the press where it isheld While the gripping device is retracted for another stroke.

Most such mechanical means are operated by fluid pressure controls andinclude a double acting fluid piston cylinder with means for varying thefeed stroke as required by different jobs. They have a dashpot or othercushioning means to soften the feed stroke at the end of its travel andusually a self-actuating wedge-lock which serves with the cushioningmeans to prevent work slippage and rebound.

The principal problems encountered with this type of equipment are inproviding a reasonably fast work feeding stroke, with just the rightdamping, a quick return, which should also be damped, and an effectiveinterlock between the work feeding and holding grippers whereby they aremutually exclusive of each other to avoid interference therebetween. Theequipment must be relatively simple in construction, to minimize theinitial expense, relatively free of service and maintenance problems,and capable of efficient performance for all variable work strokeswithin the range of performance required.

SUMMARY OF THE INVENTION The present invention is directed to mechanicalwork handling means and more particularly to equipment for feeding stockmaterial into punch presses, stamping machines and the like. It is stillmore particularly directed to quick acting power operated work stockfeeding devices having a variable stroke and adapted to service highproduction equipment wtih precision and accuracy.

In the present invention pneumatic means are used in place of ahydraulic fluid system to move the work carriage member, grip the workstock for feed, and to hold it during the return stroke of the carriage.The two grippers are made mutually exclusive of each other and aninterlock control is provided to guard against retracting the carriagewhen the carriage gripper device is closed.

The pneumatic system includes solenoid operated control valves, actingagainst a return spring pressure, and adapted to provide alternate workfeed and work holding return strokes in closely timed sequence, inaccord with the demands of the production equipment.

Means are provided for varying the work feeding stroke of the carriagemember and for damping or cushioning both the feed and return strokes ofthe carriage by separate variable controls, in a simple arrangement, toassure maximum efliciency in service.

To facilitate the conversion from hydraulic to pneumatic controls andoperating devices, significant innovations have been made in thediaphragm operated valve structures, for the gripping and holdingmechanisms, in the damper, in the control system, as mentioned briefly,and elsewhere as *will be more fully described in the detaileddescription provided hereinafter.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view of thestock feeding device of this invention with one side wall partiallycutaway to better show the traveling member.

FIG. 2 is a top plan view of the stock feeding device with one side andan extended end cut away in part to better fit the drawing page.

FIG. 3 is an enlarged cross-sectional view through the stock feedingdevice as seen generally in the plane of line 33 of the first drawingfigure.

FIG. 4 is a cross-sectional view taken in the plane of line 4-4 in FIG.3, and showing the damper device for cushioning the stroke of thetraveling gripper member.

FIG. 5 is a cross-sectional view through the damper valve housing,showing the means of individual adjustment for feed and return strokes,as seen in the plane of line 5-5 of FIG. 4.

FIG. 6 is a schematic illustration of the pneumatic control circuit.

FIG. 7 is a schematic illustration of the electrical control circuit.

DETAILED DESCRIPTION The present equipment is for use with presses andstamping machines, or the like, which have a vertically reciprocal ramacting relative to a platen on which the work stock is received, whilethe ram is raised, and is adapted to feed the stock into the machineautomatically and in timed sequence with the operation of the productionmachine. Accordingly, it is located near and is preferably attached tothe production machine to support the work stock as it is fed across theplaten a predetermined distance, in timed sequence with the raising ofthe ram, as required by the size of the work pieces being formed.

A base or frame member is provided of snflicient length to support andalign the work stock being fed into the production machine and withsuitable guides at opposite ends for a side edge of the strip or sheetmaterial to keep it straight. A carriage member, on guide rails betweenthe ends of the base frame, is moved back and forth by a double actingpiston cylinder and is formed to receive and grip the stock material asit is moved forward, release it at the end of its forward stroke, andreturn for successive work feeding strokes.

The gripper provided on the carriage member is operated by a solenoidcontrolled air valve and a similar gripper with like controls isprovided on the base frame to hold the work stock while the carriagemember is returned for its next work feeding stroke.

Such work feeding and holding devices are made mutually exclusive ofeach other by interlocking controls so that they are never at crosspurposes and, at the same time, one or the other thereof is in serviceat all times for faster feed rates and positive work stock location inthe production machine.

An air operated buffer or damper is provided in the work carriage and isdisposed for service at the ends of its forward and return strokes toenable fast operation without jarring effects causing work stockslippage in the grippers 0n the carriage and base frame. It includes arelatively simple double acting piston member with separate air bleedcontrols by which the cushioning effect at diiferent ends of thecarriage travel can be adjusted as best suits needs and requirements.

Referring now to the drawings, the base frame includes a casting orassembly of reasonable mass and Weight to counter the inertial forcesinvolved and comprises a bottom wall 12 extending the full lengththereof, side walls 14 and 16 and end walls 18 and 20 standing slightlyabove the side walls to serve as guides for the work stock received andmoved thereacross. A pair of guide rods or rails 22 and 24 extend inparallel spaced relation to each other between the end walls of the baseframe and above the bottom wall 12. They are received within alignedbores in the end walls and are fixed by press fitted pins 26 againstrelative movement and thereby form an integral part of the base framestructure.

The side edge of strip stock or sheet material, supported on the endwalls 18 and 20, is guided by a pin 28 on the end wall 18 and a post 30aligned therewith and standing up from the bottom wall of the baseframe. To accommodate sheet material and strip stock which overhangs theside wall of the base frame to any appreciable extent, outriggers 32 and34 may be provided on the end walls with interconnecting roller tracks36 or like means as best serves the need.

On the guide rods 22 and 24 is provided the carriage member 40 which isactuated between the end walls of the base frame by a double actingpiston cylinder member 42 fastened to the end wall 20 and having itspiston rod 44 extended therethrough and engaged to the carriage member.

The carriage member 40 is a casting which includes interconnectedcylindrical portions 46 and 48 receiving the guide rods 22 and 24therethrough and provided with bushings 50 for the free sliding movementof the carriage member back and forth on them under the control of thepiston rod 44 engaged to the interconnecting web 52 therebetween. Thepiston rod is formed to include a shoulder 54 engaging the end wall ofthe carriage member, for pushing it in one direction, and has a slightlyundersized close fitting extension 56 through the web wall 52, assuringalignment therewith, and a shoulder forming end cap 58 fixed thereto onits extended end, as by lock screw '60, for pulling the carriage back toits retracted position.

The stroke or travel of the carriage member 40, between the end walls ofthe base frame and relative thereto, is determined by a stop pin 62,fastened by a lock screw 64 on a block 66 on the inner face of end wall18, and by an adjustable stop provided by the threaded screw member 68extending through a fitting 70 fastened to the inside of the other endwall member 20. The fixed stop pin 62 will be noted as holding the endsof the carriage guides, provided by cylindrical portions 46 and 48, fromengagement with the end wall 18 and it will be likewise appreciated thatthe adjustable stop precludes engagement of the carriage with the otherend wall and any other structure provided thereon.

The adjustable stop extends through a threaded bore in the end wallfitting 70 that is slotted (not shown) so that it may be contracted, asby screw 72, to fix the adjusted location of the stop and safeguard itagainst damage from impact forces.

To further prevent impact loads in slamming the carriage against theadjustable stop and, to be more precise, to damp or cushion the inertialforce of the carriage member at both ends of its feed and returnstrokes, so that it will not cause the work stock material to moverelative to the feed and holding grippers, a damper or bufferarrangement 74 is provided within the carriage member 40, as is bestshown by FIGS. 3-5 and will now be described.

A bore 76 is provided through the carriage member wall, from front toback, and is provided with a bearing sleeve 78 and a piston member 80with rod extensions 82 and 84 on opposite sides thereof which extendthrough journal bearing supports 86 and 88 at the outer ends of the borehole. Suitable seals 90 are provided in the journal bearing members, forthe piston rods that extend therethrough, and about the bearings, as at92, to provide an air tight chamber area 94 in which the piston member80 is reciprocal. The assembled parts are retained by closure plates 96and 98 with just the ends of the piston rods extending therethrough anddisposed for engagement with the stop 62, at the forward end of thecarriage travel, and the stop 68, when retracted.

The chamber area 94 in the bore hole passage 76 is charged withcompressed air, and held under such pressure by a source connection toan inlet passage 100 which is in communication with a cross passage 102and with passages 104 and 106 that are open into the ends of the chamberarea, through openings 108 and at the ends of the sleeve bearing, andwhich are aligned therewith. As shown by FIG. 5, the outer ends of thetransverse passages 104 and 106 are closed by plugs 109 while cone-pointadjustment screws 110 and 112 are received into the ends of the crosspassage 102 at their junction with the cross passage for restricting airflow therepast in accord with their respectively adjusted positions.

In use, when one of the piston rods engages a stop it forces the pistonmember 80 towards the opposite end of the chamber area 94, furthercompressing the air charge therebehind and causing the bleed-off aspermitted by the cone-point adjustment screw. The other adjustment screwwill inhibit or allow further charging of the chamber area space on theother side of the piston member in accord with its adjusted position andthereby further serves to regulate the damping efiect obtainable.

The power stroking piston cylinder 42 holds the carriage member againstthe stops at opposite ends of the base frame long enough for thebleed-down required to reset the piston member each time, for the nextfeed or return stroke, and so that the rod extensions thereof areextended for stop contact as required. During the carriage travel thebalanced pressure on each side of the piston member causes it to holdits position near one or the other end of the chamber area.

The gripper devices for engaging the stock material and moving itforward with the carriage member 40 and the one for holding the stockmaterial while the carriage is returned, are shown by FIGS. 1-3 and areidentified and 122, respectively.

The gripper arrangement 120, on the carriage member is shown mostclearly by FIG. 3 to include a housing part 124 which extends towardsone side and has a cover part 126 which forms a chamber area 128therewith and in which is provided the operative mechanism foraccomplishing the work stock engagement. This includes a verticallyreciprocal plunger 130 extending through a bearing sleeve 132 in a bore134, that intersects a side opening 136 in the lower housing part, of asize that will receive a side edge of the stock material, and alignedwith an anvil seat or button 138 on the carriage frame. The plungermember 130 includes a disc 140 secured to its upper end and a sealingring 142 about the disc and engaged with a sleeve liner 144 in the coverpart 126 which forms the inner peripheral wall of the chamber area 128.

The plunger, or gripper as more appropriately designated, is biased in aretracted position by a spring 146 under the disc 140 and engaged withthe bottom wall of the chamber area, or collar 148 of the bearing sleeve132 as shown in the drawing. Passage means 150 through the cover part126 and in open communication with the chamber area 128 over the plungerdisc 140, are connected to a compressed air source, and when the chamberarea is charged the disc 140 serves as a diaphragm or piston headforcing the plunger or gripper into holding engagement with the stockmaterial when disposed thereun er.

It will be noted that the use of the liner 144, in the chamber area 128,and more particularly fitted in the cover part 126, avoids the machiningotherwise necessary in cast parts and greatly reduces costs and serviceproblems in maintaining a close fitting air pressure responsiveassembly. Since the liner is fitted in the cover part, sealing betweenthe housing and cover part is less critical than with conventionallyknown flexible diaphragm arrangements and the structure is greatlysimplified in this respect also.

The other gripper device 122 is generally similar in construction to theone on the carriage member and so has not been shown and will not bedescribed in detail. It is not mobile but is mounted on the end wall ofthe base frame 10, in a fixed position, and is similarly aligned forwork stock engagement as received through a side opening provided in theouter disposed side thereof.

Referring now to FIG. 6, the pneumatic circuit is shown as including anair line 150 from a source of Com-. pressed air, such as is commonlyavailable in manufacturing plants and facilities. An air filter 152 andlubricator 154 are in the supply line and an air check valve 156 isprovided, as is conventional, in supplying air to the manifold line 158.From here the air supply is to control valves 160, 162 and 164 foroperating the carriage gripper 120, the holding gripper 122 and thecarriage operating power cylinder 42, respectively, as shown by airlines 166, 168, 170 and 172 to the respective operating mechanisms.

The air supply valves 160, 162 and 164 are biased to hold a firstposition, or condition, as shown schematically by springs 174, 176 and178 and in this respect it will be noted that the air supply valve 160for the carriage gripper 120 is normally open to charge the chamber area128. The valve is operated by solenoid 180 to vent the chamber area andeffect release of the work stock gripper.

Solenoid 182 Operates the holding gripper 122 from a normally ventedcondition to a charged condition, for gripping the work stock andholding it against relative movement, while solenoid 184 is operative ofthe control valve 164 for retracting the carriage member, which isotherwise held in its forwardly disposed position, by reversing thedirection of air flow to opposite ends of the power cylinder.

In FIG. 7, the electrical circuit is shown to include a master on-oifswitch 186 to a 110 volt power source. The solenoid 184 for actuatingthe control valve 164 and retracting the carriage member is connected inseries with a limit switch 188, and a manually operated switch 190,across the power supply and ground return lines 192 and 194. Thesolenoid 180 for inactivating the carriage gripper valve 160 is providedin a connection 196, across the control switch 190 and the solenoid 184,and the solenoid 182 for activating the holding gripper valve 162 is ina connection 198 in series with a limit switch 200 across the carragieretracting solenoid 184.

The manually operated control switch 190, between the limit switch 188and solenoid 184, is an interlocking switch with circuit making means202 in a connection 204 by-passing the limit switch 188, and operativeof the carriage gripper solenoid 180. When the switch 190 is open thecircuit making means 202 are closed and the solenoid 180 is energized tohold the carriage gripper open. Consequently, the carriage cannot beinadvertently retracted while the carriage gripper is closed.

A connection 204 is provided across the limit switch 200 and includes amanually operated control switch 206 for effecting single strokeoperation, for pilot run purposes, or continuous automatic operation.

From the foregoing description it will be appreciated that the controlvalves in the pneumatic system are biased to provide air pressure to thepower cylinder 42 to move and hold the carriage member in its forwardstock feeding position, 'to charge the carriage gripper 120, and to ventand make inactive the stock holding gripper 122. The solenoid controlsare to vary these conditions and only two limit switches are needed toaccomplish the subsequent sequence of operations required.

Although not specifically shown in the drawings, it will be appreciatedthat the limit switch 188 is provided on the production machine and isadapted to be closed during the downward stroke of the ram; so that thesolenoid 184 is energized and the control valve 164 is shifted to causethe carriage member 40 to be retracted. The limit switch 200 is alsoprovided on the production machine and is normally closed, also, duringthe working stroke of the ram, so that the solenoid 182 is energized andthe control valve 162 is shifted to charge the holding gripper 122 whilethe carriage member is being retracted. The solenoid is energized withthe carriage return solenoid 184, provided switch is closed, and thiscauses the control valve 160 to be shifted to vent and accordinglyrelease the carriage gripper 120 for the carriage return stroke.

When limit switch 188 is opened all of the solenoid controls areinactivated and the control valves shift to their biased positionsreleasing the holding gripper 122, setting the carriage gripper 120 andcharging the feed cylinderto move the work carriage, with the work stockmaterial, towards the production machine.

I claim:

1. In a device for intermittently advancing work stock material into aproduction machine and including a base frame having a carriage memberslidably mounted thereon and a gripper on said carriage member forengaging and holding work stock material thereto, the improvementcharacterized by:

air pressure responsive means operatively connected to said carriagemember and to said gripper and having a source of air under pressureconnected thereto,

passage means between said source and said responsive means biased toprovide open communication therethrough for charging said gripper andfor moving and holding said carriage member in a forwardly advancedposition,

means for shifting said passage means in response to cyclic operation ofa work stock using machine for discharging said gripper and releasing itand for retracting said carriage member via the responsive meansoperative thereof,

a second gripper provided on the base frame and including air pressureresponsive means connected to said air pressure source and havingpassage means interposed therebetween and biased to precludecommunication therethrough and said shifting means operatively connectedthereto for charging said second gripper alternately with respect tosaid first mentioned gripper,

a source of electrical power and an electrical circuit wherein saidshifting means includes solenoid operated means synchronously operativeof said passage means and having a common limit switch control foractivation thereof,

and interlocking switch mechanism in said electrical circuit forprecluding activation of the solenoid operated means operative of thepassage means effecting retraction of said carriage member and actuationof said second gripper and providing for activation of the solenoidoperated means effecting the inactivation of said first gripper.

2. In a device for intermittently advancing work stock material into aproduction machine and including a base frame having a carriage memberslidably mounted thereon and a gripper on said carriage member forengaging and holding work stock material thereto, the improvementcharacterized by:

air pressure responsive means operatively connected to said carriagemember and to said gripper and having a source of air under pressureconnected thereto,

passage means between said source and said responsive means biased toprovide open communication therethrough for charging said gripper andfor moving and holding said carriage member in a forwardly advancedposition,

means for shifting said passage means in response to cyclic operation ofa work stock using machine for discharging said gripper and releasing itand for retracting said carriage member via the responsive meansoperative thereof,

means for damping the travel of said carriage member at opposite ends ofsaid base frame and including a chamber area provided within saidcarriage member and connected to said pressure source,

a piston member within said chamber area and having means operativethereof extended in air sealed relation through the end walls of saidcarriage member for arresting engagement with stop means provided onsaid base frame,

and passage means connected to opposite ends of said chamber area andwith said air pressure source and having separate means for regulatingthe air flow thereto and from.

3. In a device for intermittently advancing work stock material into aproduction machine and including a base frame having a carriage memberslidably mounted thereon and a gripper on said carriage member forengaging and holding work stock material thereto, the improvementcharacterized by:

air pressure responsive means operatively connected to said carriagemember and to said gripper and having a source of air under pressureconnected thereto,

passage means between said source and said responsive means biased toprovide open communication therethrough for charging said gripper andfor moving 8, and holding said carriage member in a forwardly advancedposition,

means for shifting said passage means in response to cyclic operation ofa work stock using machine for discharging said gripper and releasing itand for retracting said carriage member via the responsive meansoperative thereof,

means for damping the travel of said carriage member at opposite ends ofsaid base frame and including a chamber area provided within saidcarriage member and connected to said air pressure source,

a piston member within said chamber area and having means operativethereof extended in air sealed relation through the end walls of saidcarriage member for arresting engagement with stop means provided onsaid base frame,

passage means connected to opposite ends of said chamber area and withsaid air pressure source and having separate means for regulating theair flow thereto and from,

and said passage means including a manifold passage connected to saidair pressure source, disposed through the end walls of said carriagemember, and having said regulating means engaged opposite ends thereof.

References Cited UNITED STATES PATENTS 3,329,327 7/ 1967 Scribner 226162X 3,429,493 2/ 1969 Lehmann 226-162 X 3,438,557 4/1969 Lehmann 226-162 XALLEN N. KNOWLES, Primary Examiner US. Cl. X.R.

